[16a-B5-1~13] 12.1 Fabrications and Structure Controls

[16a-B5-5] Optical Properties of Polymer Complex Nanocrystals Having Viologen Unit on the Nanocrystal Surface

〇Ryuju Suzuki¹, Tsunenobu Onodera¹, Hitoshi Kasai¹, Hidetoshi Oikawa¹ (1.IMRAM, Tohoku Univ.)

Keywords:polymer complex, nanocrystals, viologen

Metal-organic complex crystals exhibit unique optical, electronic and magnetic properties. Especially, polymer-metal complex crystals have coordinatively-unsaturated center metal or ligand molecules exposed on the surface of crystals, where we would perform sophisticated surface modification so as to modulate and/or tune the unique properties. On the other hand, nanocrystals have large specific surface area, compared to bulk crystal. However, it is frequently difficult to nanocrystallize polymer-metal complexes, due to their poor solubility. In addition, since well-control of inorganic/organic interface structure has not still been achieved enough, research on metal-organic complex nanomaterials has been far behind from both viewpoints of foundation and application. In the present study, we have developed a useful method to prepare a well-defined metal-organic complex nanocrystals. In this method, complex formation would occur on the previously-prepared organic ligand nanocrystals with large surface area. As a result, insoluble main-chain polymer-metal complexes, which show luminescence in solid state, have been nanocrystallized successfully. Especially, bipyridine complex (L = bpy) nanocrystals were obtained as well-defined pallarerogram plate. From TEM observation and analysis of electron diffraction pattern, it is found that (010) plane of bipyridine complex nanocrystals has grown well, that is, the terminal chain would be located on the (010) plane of nanocrystals as a dangling bond. So, we have tried to modify the surface of nanocrystals by end-capping the terminal chain of polymer complex. Actually, Prussian blue (PB) nanoparticles were selectively adsorbed on the (010) plane of polymer-metal complex nanocrystals. Ligands having N-terminal located on the surface would bind to PB nanoparticles. So, we have tried to modify the surface of nanocrystals through methylation of the bipyridine with iodemethane. As a result, luminescence peak position of nanocrystals was blue-shifted. In addition, the pattern of powder XRD was not changed before and after the reaction. These facts indicate iodemethane reacted only on the surface of nanocrystals, and would provide a platform to even more functionalize the nanocrystals.